From EP 495 696 A1, a fitting of the type discussed here for a flat conductor rail is known, wherein two electrical conductors are attached to the two flat sides of the rail and are separated from each other by a thin, strip-like insulating web. The housing of the fitting is comprised of two separate housing parts made of an insulating material, the parts being held together by two spring clips provided on opposite sides thereof. In both housing parts, resilient contacts are arranged which contact the conductors and which are connected to connecting cables laterally led out of the housing parts. Attachment of these two spring clips is cumbersome insofar as for this purpose the two housing parts must be held in position and held tightly against slipping off, so that at least for this two hands are required. Moreover, the two spring clips can be mounted only one after the other, thus also requiring separate manipulations.
Furthermore, from DE 39 19 201 A, a power supply for lighting fixtures is known which comprises a conductor rail and fittings which are associated with the lighting fixtures and which are to be fastened to the conductor rail. The conductor rail in that instance consists of two square metal sections interconnected by means of insulators arranged in spaced relationship in blind holes, the insulators simultaneously serving for the attachment of suspending devices. The fitting is designed as a U-shaped housing open on one side and configured like a bow which is insulatingly slipped onto the metal sections from the side; a current is collected via countersunk screws which are screwed therethrough and which contact the metal sections. On the conductor rail, a lighting fixture is attached to which lines are led which are housed in cavities provided in an insulation means of the fitting and which are connected with the screws in a manner not explained in detail. If the conductor rail is under current during mounting or dismounting of this fitting, there is the risk of short circuiting if one of the screws projects and thus conductively bridges the space between the metal sections.